Protective footpad assembly



Oct. 18, 1955 H. F. KROHN ETAL 2,720,714

PROTECTIVE FOOTPAD ASSEMBLY Filed Aug. 15, 1952 5 Sheets-Sheet l g 6 INVENTORS FTLQQ lckar' d MFZ 1m Wberf F. ffro/m g 5mm BY ATTORNEY Oct. 18, 1955 H. F. KROHN ET AL PROTECTIVE FOOTPAD ASSEMBLY 3 Sheets-Sheet 2 Filed Aug. 15, 1952 ATT )RNEY F m er/ F $67;

Rickar Wise 15g Oct. 18, 1955 KRQHN ETAL 2,720,714

PROTECTIVE FOOTPAD ASSEMBLY Filed Aug. 15, 1952 3 Sheets-Sheet 3 INVENTORS WSQSS ZZZLZIZ,

ATTORNEY 2,720,714 PROTECTIVE FOO'TPAD ASSEMBLY Herbert F. Krohn, Bethlehem, 132.,

Alexandria, Va., and William 0. Ohio; said Sassaman assignor erica as represented by Richard M. Flynn, Sassaman, Akron, to the United States of the Secretary of the Army Our invention relates to a protective footpad for use in clearing mine fields.

A primary object of the invention is to provide a footpad assembly, constructed somewhat on the snowshoe principle, for use by military personnel in detecting and clearing mine fields, the assembly including a soft compressible element extending over a relatively wide area of the ground and exerting a low unit pressure upon the ground.

A further object is to provide a protective footpad assembly embodying an adjustable quickly releasable foot harness.

A further object of the invention is to provide a device of the above-mentioned character which is compact and simplified in construction, lightweight, durable and relatively cheap to manufacture.

Other objects and advantages of the invention will be of the following description. In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a perspective view of a protective footpad embodying our invention,

Figure 2 is a plan view of the same,

Figure 3 is an enlarged central vertical longitudinal section on line 3-3 of Figure 2,

Figure 4 is an enlarged transverse vertical section on line 4-4 of Figure 2,

Figure 5 is a similar section on line 5-5 of Figure 2,

Figure 6 is an exploded perspective view of the footpad assembly,

Figure 7 is an enlarged fragmentary vertical cross sectior through the rear end portion of the footpad assembly, an

Figure 8 is an enlarged fragmentary vertical cross section on line 88 of Figure 2.

in the drawings, where for the purpose of illustration is shown a preferred embodiment of our invention, the numeral 12 designates a soft compressible pad assembly mately one inch thick, approximately three inches may be varied somewhat if 12 is elongated, as shown, and rear ends. The pad proximately twenty inches thick, although this thickness desired. The pad assembly and has semicircular forward assembly 12 is preferably aplong and ten inches wide, and

these dimensions may be varied slightly as desired. The I size of the pad assembly 12 is such that the weight of the Patented Oct. 18, 1955 wearer is distributed over a substantial area, and a low unit pressure is exerted upon the ground containing the explosive mines.

We also contemplate employing a single foam rubber slab only instead of the slabs 14 and 15. Such a slab will be preferably about two inches thick and formed of cored synthetic foam rubber.

A rubberized waterproof fabric sheet or sealer 17 is interposed between the intermediate and lowermost slabs 14 and 13, and cemented to these slabs with Waterproof cement. The uppermost slab 15 is likewise cemented to the intermediate slab 14, and the three foam rubber slabs are thus permanently joined together with sheet 17 for forming the pad assembly 12. A relatively narrow continuous marginal portion 18 of the fabric sheet 17 extends beyond the marginal edge of the pad assembly 12, for a purpose to be described.

A foot harness and plate assembly 19 is provided, and comprises a lower flat, thin plate. 20 of aluminum or the like. The lower plate 20 has a plurality of spaced openings 21, extending therethrough and distributed over a major portion of the area of the same, and adapted to register with the openings 16 in the top of the slab 15.

An upper thin aluminum plate 22 is mounted upon the lower plate 20 and spot welded or otherwise permanently rigidly secured thereto, along the marginal edge portions 23 of the plates. The plate assembly 19 has semi-circular forward and rear ends, like the pad assembly 12 and also substantially the same length and width as the pad assembly, so that when the plate assembly 19 is mounted upon the pad assembly 12, the marginal edges of the two assemblies will coincide.

Inwardly of the marginal edge portion 23 of the upper plate 22, the same has a raised central fiat portion or wall 24, extending over a major portion of the area of the plate assembly 19, and integrally secured thereto by a continuous inclined wall or flange 25. The raised portion 24 is preferably depressed at spaced intervals along the longitudinal center line of the device to form depending reinforcing bosses or feet 26, having their bottoms 27 spot welded to the lower plate 20. The bosses 26 are located at the area where the weight of the wearer is concentrated, and prevent crushing of the raised portion 24. Near the rear end of the raised portion 24, and at the transverse center of the same, an opening is provided which receives a short upstanding vent tube 29, rigidly secured therein by welding or the like. This vent tube 29 communicates with the space between the raised portion 24 and the lower plate 20 having the openings 21, leading into the openings 16.

Near the forward end of the raised portion 24 and at the transverse center of the same, a channel plate 30 is rigidly mounted thereon by spot welding or the like, and this channel plate has its longitudinal edges upturned to form parallel longitudinal guides 31 above the channel plate 30.

A flat rigid heel plate 33 is positioned above the raised portion 24, slightly forwardly of the vent tube 29 and at the transverse center of the device. A flexible heel receiving a band 34 of heavy cotton duck or the like has a lower marginal portion 35, disposed between the heel plate 33 and raised portion 24, and permanently secured to the heel plate 33 by rivets 36 or the like. The heel plate 33 is rigidly secured to the raised portion 24 by screws 37, engaging in tubular nuts 38, permanently rigidly secured within openings formed 11 the raised portion 24. The tubular nuts 38 have their lower ends extending through clearance openings 39 formed in the lower plate 20, as shown.

A rigid substantially fiat sheet metal toe plate 40 is arranged above the channel plate 34) with its opposite longitudinal edges arranged laterally outwardly of the guide flanges 31, Figure 4. An adjustable slide 41 is interposed between the toe plate 40 and channel plate 30, and has its central portion raised for supporting the toe at an elevation above the guides 31, Figure 4. The slide 41 has downwardly offset longitudinal flanges 42, slidably engaging the guides 31, as shown. A flexible toe holding band 43 of heavy cotton duck or the like is disposed between the toe plate 40 and slide 41, and extends for'a substantial distance transversely beyond the longitudinal edges of the toe plate 40. Rivets 44 near the longitudinal edges of the toe plate 40 extend through the toe plate and toe holding band 43 for securing the same together, Figure 4. Additional rivets 45, arranged laterally inwardly of the flanges 42 extend through the toe plate 40, band 43 and slide 41 for rigidly securing these elements together, Figure 4.

The toe plate 40, flexible band 43 and slide 41 thus constitute an adjustable toe holding unit adapted to be moved longitudinally of the channel plate 30. In order that the toe holding unit may be locked in a selected adjusted position, a plurality of longitudinally spaced tubular nuts 46, similar to the nuts 38 are permanently rigidly secured within openings formed in the raised portion 24, at the transverse center of the same and beneath the channel plate 30. The channel plate 3th has clearance openings 47 formed therein, Figure 8, for receiving the upper ends of the nuts 46, and the lower ends of these nuts may project through clearance openings 48, formed in the lower plate 20 at the transverse center of the same. The toe plate 40 is provided at its transverse center and near its rear end with an opening 49, receiving a screw 50 which is engageable in any of the nuts 46 to releasably lock the adjustable toe holding assembly in the selected adjusted position.

The flexible heel and toe receiving bands 34 and 43 are provided at corresponding sides with adjusting buckles 53 of any preferred type, permanently secured thereto by riveting, or the like. Transverse instep and toe binding straps 54 and 55 are provided, and having corresponding ends stitched or otherwise permanently secured to a longitudinal strap 56, arranged at the side of the foot remote from the buckles 53, and having a short pull loop 56, secured thereto near its longitudinal center. The transverse straps 54 and 55 are adjustably received by the buckles 53 when the foot of the wearer is inserted into the foot harness, as illustrated in Figure 1. The straps 54 and 55 are provided near their ends adjacent to the strap 56 with female snap fastener elements 57, receiving male snap fastener elements 58, carried by the adjacent sides of the heel and toe bands 34 and 43.

A rubberized waterproof fabric gusset or sheet 59 extends entirely about the marginal edges of the uppermost and intermediate slabs and 14, and has its lower marginal portion stitched at 60 to the marginal portion 1% of the sheet or barrier 17. The upper marginal portion 61 of the gusset 59 is folded over the marginal portion 23 of the upper plate 22, outwardly of the inclined wall 25, as shown. The marginal portion 61 may be slit or pleated at intervals, Figure 6, and cemented to the upper plate 22 with waterproof cement. A chafing strip 62 of heavy rubberized fabric is cemented to the gusset 59 where the same passes about the edge of the plate as-' sembly 19, and this chafing strip protects the gusset against abrasion. It is thus seen that the sheet 17, gusset 59 and plate assembly 19 form a watertight envelope or enclosure for the upper and intermediate slabs 15 and 14, the lowermost slab 13 being uncovered and exposed. The gusset 59 also serves to secure the compressible pad assembly 12 to the plate assembly 19.

A rubber hose or tube 63 has its lower end receiving the upstanding vent tube 29, and is secured thereto by a clamp 64. An adjustable leg strap 65 is slidably mounted upon the hose 63, and adapted to embrace the leg of the wearer above the ankle. The hose 63 may be ar ranged inside or outside of the trouserleg, as preferred.

When the footpads are properly applied to the feet of mine clearing personnel, such personnel may walk over the mine fields with greatly reduced liability of exploding the mines, which are set to explode at a predetermined pressure upon the ground. The weight of the wearer is distributed over a relatively large area of the ground by the footpad assemblies which embody the snowshoe principle. Since the multiple thickness pad assembly 12 is soft and compressible, this further greatly reduces the liability of exploding the mines. Also, the weight transmitted to the ground through the compressible pad is uniformly distributed, because the rigid plate assembly 19 extends over the entire area of the compressible pad.

The vent tube 29 and hose 63 allow air to enter an exhaust from the space between the lower plate 24 and raised portion 24, as the slabs 14 and 15 are expanded and compressed during walking. The air from the cellular slabs 14 and 15 enters the space between the upper and lower plates through the openings 16 and 21. This arrangement makes the pad assembly more yielding and compressible, since the air is not trapped inside of the cellular slabs 14 and 15, but can enter and leave the slabs freely by way of the tube 63.

When it is desired to remove the pad assembly from the foot quickly, in an emergency, the wearer merely grasps the pull loop 56 and disengages all of the snap fastener elements 57 and 58 with one pull. The wearer can then step freely from the pad assembly and it is not necessary to loosen the buckets 53.

The entire assembly is relatively light, and the arrangement whereby the upper and intermediate slabs 15 and 14 are held within the Waterproof enclosure prevents these slabs from soaking up moisture and deteriorating or unduly increasing the weight of the assembly. The lowermost slab 13 may be stripped off and replaced by a new slab when the same becomes worn or deteriorated.

It is to be understood that the form of our invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the nature or character of the materials as well as the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described our invention, we claim:

1. A protective footpad assembly comprising a thick compressible sponge rubber pad having a ground contact area substantially greater than that of a shoe, said pad including a plurality of superposed slabs, a flexible moisture-proof element enclosing at least the uppermost slab of the compressible pad, a first plate mounted upon the compressible pad and having openings, a second plate secured to the first plate and spaced above the first plate over a major portion of the area of the compressible pad for providing an air space between the first and second plates, air vent means carried by the second plate so that air may enter and be expelled from the space between the first and second plates when the pad is compressed during walking, and foot harness means mounted upon the second plate for receiving and holding the foot of the wearer.

2. A protective footpad assembly comprising a soft compressible pad of substantial ground contact area, said pad being formed of a plurality of superposed layers, the uppermost layer of the pad having a plurality of spaced recesses formed in its top surface, a substantially rigid plate assembly mounted upon the uppermost layer and substantially covering the same and provided in its bottom with a plurality of spaced apertures registering with the recesses of the uppermost layer, a flexible sheet surrounding the marginal edge of the plate assembly and compressible pad and secured to the plate assembly and extending between the lowermost layer and next uppermost layer of the compressible pad and serving with the plate assembly to provide a watertight enclosure for the POIfiQDs of the compressible pad above said lowermostlayer, the plate assembly having an upwardly olfset wall forming an air space communicating with the openings of the plate assembly and said recesses, air vent means leading from the air space of the plate assembly, and an adjustable foot harness carried by the plate assembly.

3. A protective footpad assembly comprising a compressible pad having a ground contact area substantially greater than that of a shoe, a substantially rigid plate secured to the top of the footpad and extending over a major portion of the area of the footpad, a heel-receiving element carried by the plate, a toe-receiving element secured to the plate and spaced forwardly of the heel-receiving element, snap fastener means secured to the heel and toe-receiving elements, and an adjustable quick releasing foot harness connected with the heel and toe-receiving elements and engaging the snap fastener means.

4. A protective footpad assembly comprising a thick compressible foam rubber pad having a ground contact area substantially greater than that of a shoe, a substantially rigid plate assembly mounted upon the compressible pad and substantially covering the same, a heel-receiving band secured to the plate assembly near the rear end of the same, a longitudinally adjustable toe-receiving band secured to the plate assembly forwardly of the heelreceiving band, the heel and toe-receiving bands being provided at corresponding sides with snap fastener elements, adjustable instep and toe binding straps connected with the heel and toe-receiving bands respectively and extending transversely of the foot and having snap fastener elements for coaction with the snap fastener elements of the heel and toe-receiving bands, dinal pull element connected with binding straps for quickly releasing the instep and toe binding straps.

and a longituthe instep and toe the snap fasteners of 5. A protective footpad assembly comprising a soft compressible pad having a ground contact area substantially larger than that of an ordinary shoe, said pad being formed of a plurality of superposed layers of compressible material, the uppermost layer of the pad having a plurality of spaced recesses formed in its top surface, a first substantially flat plate mounted upon the uppermost slab and substantially covering the same and having a plurality of spaced apertures registering with the recesses of the uppermost layer, a second plate mounted upon the first plate and secured thereto near the margins of the first and second plates and having a portion spaced above the first plate forming an air space between the first and second plates in communication with said recesses, an air vent tube connected with the second plate and communicating with the air space between the first and second plates and adapted to extend above the footpad assembly adjacent to the leg of the wearer, an envelope of substantially waterproof material inclosing at least the uppermost layer of compressible material, and foot harness means carried by the footpad assembly for receiving the foot of the wearer.

References Cited in the file of this patent UNITED STATES PATENTS 683,595 Drouillard Oct. 1, 1901 1,851,778 Skillen Mar. 29, 1932 2,367,219 Kearny Ian. 16, 1945 2,430,466 Hedman Nov. 11, 1947 2,469,969 Lee May 10, 1949 OTHER REFERENCES Popular Science, Sept. 1948, page 133. 

